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Power Supplies I Product News Ultra compact 15-40 Watt power supplies

with PCB or chassis mount options XP Power has announced two additions to its range of ultra compact high power density AC-DC power supplies. New products include the introduction of the encapsulated single output ECE series, and multiple output models of the existing ECL family.

The ECE20 are encapsulated PCB mount

20 Watt devices, measuring just 27.7 x 52.4 x 23.0 mm (1.07 x 2.06 x 0.91 inches), while the ECE40 units measure only 38.1 x 78.7 x 27.9 mm (1.50 x 3.10 x 1.10 inches) and have up to 40 Watts output. The ECE40 are also encapsulated and are available in either a PCB mount version, or chassis mount package with screw terminals. Both the ECE20 and ECE40 series have a power density of 9.97 / 7.82 Watts per cubic. The ECE20 is 38 percent smaller than the previous 15 Watt models.

They are believed to be the smallest 20 and 40 Watt encapsulated product on the market and have the highest power density in their respective categories. Providing all the popular nominal output voltages from +3.3 to + 48 VDC, the single output ECE series is ideal for a broad range of low power applications in space constrained designs.

Also being released are dual and triple

output 15 Watt and 30 Watt versions of the popular ECL series. These compact supplies, with sizes starting from just 30.7 x 62.0 x 24.4 mm (1.20 x 2.44 x 0.96 inches) for the 15 Watt open frame PCB mount models, are available in open frame or encapsulated PCB mount, and chassis mount with either connectors or screw terminals. The new multiple output models provide combinations of +/-12, +/-15, 5/12, 5/+/-12 and 5/+/-15 VDC outputs. All units across the ECE and ECL ranges feature a no load input power of less than 0.3 W helping customer's end-products comply with internationally recognized energy efficiency standards. Both series also meets XP Power's 'green power' limits. Operating from as low as -10 degrees C and up to +50 degrees without derating, the converters can operate in most environments without the need for additional heat sinks or forced airflow. Operation up to +70 degrees C is possible with derating.

The units comply with EN550022 level B standard for both conducted and radiated emissions without the need for additional filtering components.

XP Power |

HiTek Power develops custom high-voltage power supply for Chinese scientific research

Leading-edge scientific research being undertaken in China is being aided by a customised high-voltage power supply developed by HiTek Power for the Institute of Applied Electronics at the China Academy of Engineering Physics.

The HiTek Power supply is being used in a terahertz free electron laser (FEL) driven by an accelerator and provides power for an electron gun. The terahertz FEL light source is a tool used in basic science research within the fields of physics, chemistry, life sciences and medical imaging. However, the demanding requirements for the quality of electron beam, such as very small energy spread, require very high stability from the power supply. Large peak power is required for the study of new non-linear phenomena in advanced materials and devices and a large average power was specified to allow "full-field" real-time image capture – in effect, terahertz movies. The academy required a 10kW, 400kV power supply that met its specific need for very high stability. Although the converter unit would be housed in a 3U 19-inch rack-mountable chassis, the modular high-voltage unit, using 20 HV disks, had to fit inside a sealed chamber. This would then be filled with SF6 insulating gas to a pressure of up to approximately 10 Bar. This presented a number of mechanical design challenges in addition to the need to meet a demanding electrical specification. The electrical and mechanical design teams at HiTek Power worked closely together in conjunction with China Academy to develop this custom system. The power supply is based on HiTek Power’s established 10kW Series OL10K range. It is a high-stability negative-polarity supply with industry-leading levels of line and load regulation and ripple. It incorporates HiTek Power’s

proprietary Arc Count and Extinguish (ACE) arc management system, which continuously monitors the output of the supply and can be programmed to perform a number of different actions if one or more arcs are detected. This dramatically improves the reliability of the entire system in which it is installed. A new resistance divider column was designed in two 200kV sections to meet tooling, pressure chamber and oven restrictions and a design was developed to mechanically and electrically couple the two dividers. In addition a new RS232 interface unit was designed to provide the required control functionality for the converter unit.

Using its finite element analysis software, Hitek Power carried out a detailed voltage stress analysis of the HV unit mounted within the pressure vessel, to minimise voltage stress within the system.

The mechanical design team worked on a number of special fittings, mainly to accommodate the requirements of the high- pressure chamber. New electrical feedthroughs were designed to be pressure-sealed to the electrical insulators with o-rings. A new reinforced electrical insulator plate was designed to withstand the forces caused by the pressure and the weight of the equipment. A new reinforced circular base plate was designed to be pressure-sealed to the electrical insulator with o- rings. Features for sealing the base plate to the pressure chamber were designed to meet customer specifications. A detailed analysis was then carried out to ensure that all mechanical elements met the demanding system specifications.

HiTek Power System |

New power analyser can identify problems associated with “green” devices

Outram Research Ltd – a specialist manufacturer of leading-edge power quality analysers – has announced that the PM7000 analyser now offers additional features to help identify and resolve power quality problems caused by the increasing use of energy-efficient appliances and renewable power sources.

Harmonic distortion can become a significant problem, as more and more mains-connected devices use high-efficiency switching power supplies or inverter-type power sources and power is increasingly supplied from renewable sources that require a DC to AC conversion. Switching power supplies, which are

used in products such as variable frequency motor drives (VFDs), IT equipment, home entertainment systems and LED lighting tend to draw power through current spikes at the peak of the mains cycle. Low-energy compact fluorescent light bulbs (CFLs) also exhibit the same behaviour. Drawing current at the peaks causes harmonic distortion which results in power being wasted in motors and transformers. It can also cause increased noise and wear on bearings and in extreme circumstances the equipment can fail due to overheating. Renewable energy sources such as solar cells may require conversion of DC power to AC. If the output AC waveform is an

imperfect sine wave, this harmonic distortion can have a similar effect. The Outram Ranger PM7000 is the first power quality analyser to offer analysis of the phase difference between the harmonic voltage and current, giving additional detailed information about the source of distortion of the mains waveform. Modern switching power supplies often exhibit problems at high frequencies, and so the PM7000 offers one of the industry’s highest sampling rates, recording up to the 50th or 120th harmonic. “Visibility is critical to help engineers solve the increasing problem of harmonic distortion of the mains waveform,” said

John Outram, Managing Director of Outram Research. “By providing information on the phase difference between current and voltage up to the 120th harmonic we help engineers to identify and resolve problems more quickly and efficiently.”

The new harmonic distortion analysis features are now provided as standard across the family of Outram Ranger PM7000 power analysers. New firmware to upgrade existing analysers is available on request.

Outram Research Ltd |

32 July/August 2011

Components in Electronics

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